The religion of peace...the closer the blood relative, the more likely was there to be a schizophrenic illness.

Massive inbreeding within the Muslim culture during the last 1.400 years may have done catastrophic damage to their gene pool. The consequences of intermarriage between first cousins often have serious impact on the offspring's intelligence, sanity, health and on their surroundings

The most famous example of inbreeding is in ancient Egypt, where several Pharaonic dynasties collapsed after a couple of hundred years. In order to keep wealth and power within the family, the Pharaohs often married their own sister or half-sister and after a handful of generations the offspring were mentally and physically unfit to rule.

Another historical example is the royal houses of Europe where royal families often married among each other because tradition did not allow them to marry people of non-royal class. The high amount of mentally retarded and handicapped royalties
throughout European history shows the unhealthy consequences of this
practice. Luckily, the royal families have now allowed themselves to
marry for love and not just for status.more...